Mixing vessels may be used in a variety of commercial and industrial processes. A variety of materials may be mixed in a mixing vessel. Different materials and different processes may require different amounts of shear and flow patterns to properly mix the ingredients, maintain the ingredients in suspension, and circulate the ingredients within the vessel. The size, shape, location, orientation, and rotational speed of the mixing vessel impeller may be factors in producing specific flow patterns tailored for a particular product.
A mixing vessel without baffles may not produce enough shear or turbulence to mix the ingredients. Therefore, many mixing vessels may include fixed baffles that may influence the mixing action and flow patterns. The number, size, location and geometry of baffles may vary widely, generating both localized high shear between the baffle and impeller blades, and generating circulating currents that may promote the homogeneity and suspension of ingredients. A configuration of impeller and baffles that may be optimized to produce one product may be unsuitable for a different product.
The flow patterns and circulating currents may also be influenced by the shape of the vessel itself. Typically, a vessel having a concave bottom may produce better vertical dispersion because the liquid may be slung out radially from the impeller and may be gently turned upward when the liquid moves toward the vessel wall. Flat-bottomed mixing vessels may not do this function nearly as well, and may have very poor flow patterns. Acceptable flow patterns and methods of mixing a material may be discovered by adding and experimenting with various types of baffles.
In the past, new mixing vessels with optimized geometry were constructed for, and exclusively dedicated to, a specific process or product. As an alternative, existing plain mixing vessels that were, at first, completely unsuitable for a particular process, were retrofitted by adding permanently welded baffles. In such mixing vessels, it may be relatively easy and common practice to make small variations in the mixing action and fine tune it to slightly different processes by changing the impeller or its rotational speed. Changing the baffling may have a much larger effect, but it may be costly to construct a new mixing vessel each time one wishes to alter a baffle arrangement. It may also be costly to remove welded baffles and reweld new baffles in a mixing vessel.
In a manufacturing scenario where more than one product is made, for instance, the manufacturer may set up a single production line, and simply switch baffles in the mixing vessels. In a research and development scenario, the effect that each element of geometry has on the mixing process itself, or the effect that each element of geometry has on the quality of the product being produced, may be explored using many physical variations. Baffles that are easily removed and replaced in a mixing vessel may save time, money, and storage space (for multiple variations of mixing vessels), and simplify cleaning and repair of baffles. Thus, a need exists for mixing vessels having easily interchangeable baffles.
In some cases, such as laboratory bench top and glassware size vessels, a mixing vessel having the desired baffle arrangement may not be available commercially. Formulations and mixing procedures for products may be developed and tested in both small and medium scale laboratory mixers before transitioning to high rate production in full size mixing vessels. A manufacturing plant that uses 3000 gallon baffled mixers may have a laboratory where procedures are developed in quart or gallon sized mixers. Thus, there is a need to be able to adapt standard laboratory glassware mixing vessels, for instance, into scale models of larger mixing vessels, by adding baffle kits.